The present invention relates generally to a decelerator system for a work machine and, more particularly, to a decelerator system for a work machine incorporating an operator control device which allows the operator to control the engine, transmission, and brake with one command to decelerate the machine.
It is often desirable to control the drive train torque of a work machine while the work machine is digging or traveling. For example, in an earth-working type machine, an operator typically xe2x80x9cinchesxe2x80x9d the machine when working with material while providing full power to the implement hydraulics to capture the material. It is important to control the amount of drive train torque to reduce rimpull, which is useful for reducing slipping.
In one conventional method of inching, the transmission is kept in gear and the brakes are manually modulated by use of a foot pedal. In another conventional method of inching, an impeller clutch is connected between a machine""s engine and transmission. Typically, the impeller clutch is actuated through an operator pedal. The operator pedal acts to engage and disengage the impeller clutch, thereby varying the power transmitted by the drive train to slow the machine.
Most prior art methods of controlling the work machine to reduce drive train torque, reduce slipping, and prevent engine stalling are largely undesirable because they require considerable operator effort. Typically, three operator pedals are needed: one to control the engine acceleration, another to control clutch pressure, and yet another to control machine braking. Operators use all three of these pedals at various times in the work cycle, necessitating effort directed to activating pedals and changing foot positions.
An electrohydraulic control device for a drive train of a machine is disclosed in U.S. Pat. No. 6,162,146, issued Dec. 19, 2000 to Kenneth J. Hoefling (hereafter referenced as ""146). A control member produces an operator control signal. An engine control module receives the operator control signal and responsively reduces the rotational speed of the engine. A transmission control module additionally receives the operator control signal and responsively controls the engagement of a predetermined transmission clutch to reduce the transmitted torque from the transmission. As shown in FIG. 3 of ""146, the engine speed is at a maximum unless the operator manipulates the control member to reduce the engine speed and control the transmission and brake.
Accordingly, the art has sought a method and apparatus of a decelerator system for a work machine which: can be used either with a throttle lock or operator control of engine speed; has no impeller clutch and therefore does not generate clutch-related heat and wear on components; can neutralize the transmission; can be used with a traditional torque converter and transmission; may improve control of rimpull torque or ground speed on various footings; smoothes out directional shifts; requires less operator effort; facilitates greater operator comfort and confidence; may be used in a timely and efficient manner; and is more economical to manufacture and use.
The present invention is directed to overcoming one or more of the problems as set forth above.
In an embodiment of the present invention, a decelerator control system for a work machine is disclosed. The decelerator control system includes a first control member, a machine control device, an engine, at least one brake, and a transmission. The first control member is manually moveable and is adapted to produce a first operator control signal. The machine control device is adapted to receive the first operator control signal and responsively produce an engine control signal, a brake control signal, and a transmission control signal. The engine is adapted to receive the engine control signal and responsively control the speed of the engine. The brake is adapted to receive the brake control signal and responsively control an engagement of the brake. The transmission is adapted to receive the transmission control signal and responsively control an engagement of the transmission.
In an embodiment of the present invention, a method for controlling the deceleration of a work machine having an engine, a brake set, and a transmission is disclosed. The method includes the steps of reading the position of a first control device and responsively producing a first operator control signal; and reading the first operator control signal and responsively producing an engine control signal, a transmission control signal, and a brake control signal. The method also includes reading the engine, brake, and transmission control signals and responsively controlling the engine, brake, and transmission, respectively.
In an embodiment of the present invention, a method for use in a machine control system is disclosed. The method includes the steps of generating a control signal based on an operator input signal and including in the control signal values of a rate limited engine speed, a desired brake engagement, and a desired transmission engagement.